Not Divided Mod

[jibberishballr]

I was reading this thread and wondering if it works. It doesnt seem like it would be that hard to do at home. Anyone have any expierence with this.

Heres a link to what im talkin about:

http://www.dsmtuners.com/forums/showpost.php?p=50427715&postcount=20

Also i realize you cant run external once you do this.

 

[MyBeatGSX]

You still don't get it.

Answer this question for me, and then I'll tell you why non-divided is the stupidest idea ever....


Why do you want a non-divided turbine housing?

 

[flinguist]

Some turbos come with an "undivided" exhaust housing, such as the Subaru WRX turbo.

 

[DGajre777]

You still don't get it.

Answer this question for me, and then I'll tell you why non-divided is the stupidest idea ever....

Why do you want a non-divided turbine housing?

Oh no, you got me wrong. I do get it. The entire discussion was the exhaust hitting the wall on the o2 housing after it leaves the turbine housing. The Lipp o2 housing doesn't have a wall so 'in theory" without a wall, how will it affect efficiency? Are you saying that the gases from the turbine outlet and wastegate outlet meeting together affect efficiency? How is that, when the gases meet inside a regular 2G style o2 housing anyway? We all know that air (like water) will follow the least path of resistance.

As for why I want a non-divided turbine housing? MONEY! It is cheaper to get a non-divided housing and a Lipp o2 housing than to get a divided housing turbo and have to get an external wastegate to prevent boost creep. The whole idea of PTE offering undivided turbos want to prevent boost creep. There has to be an alternative to boost creep other than 1) porting 2) going to an external gate and 3) running high boost pressures. I know that on an Evo III 16G running over 18psi of boost reduces the chances of getting creep. Anyone know this psi number on a PTE BB 50 trim?

And if undivided housing turbos are such a bad idea why does Subaru have it on their cars?

 

[MyBeatGSX]

I don't want to come across as an asshole, but you obviously don't get it. Let me spell it out for you and anyone else reading.

This was discussed already. The non-divided mod prevents creep by hugely raising post turbine backpressure. The same way putting on a cat or stock exhaust prevents creep. YOU MUST UNDERSTAND THIS. It prevents creep by hurting flow. If it isn't hurting flow, it isn't preventing creep. End of story.

The exhaust does not hit the O2 housing wall. Its the fact that the turbine discharge and the wastegate discharge are able to hit each other that causes the high back pressure. Its just kills flow. End of story.

Don't you understand that if you take away this horrible flow with a better designed O2 housing, you also take away the boost creep elimination of the non-divided mod? You're reverse engineering your way back to a fully divided housing.


There is not a cheap hack to fix creep. What you're trying to do is like saying, "Hey I don't want to spend the money on an MBC, so I'll just stick a screw driver through one of my charge pipes and leave a huge hole. This should keep it from boosting to high. Hey it works right? My boost stays at 15psi!"


This is such a simple concept I don't know why everyone is having such a hard time understanding it.

 

[DGajre777]

This was discussed already. The non-divided mod prevents creep by hugely raising post turbine backpressure. The same way putting on a cat or stock exhaust prevents creep. YOU MUST UNDERSTAND THIS. It prevents creep by hurting flow. If it isn't hurting flow, it isn't preventing creep. End of story.

The exhaust does not hit the O2 housing wall. Its the fact that the turbine discharge and the wastegate discharge are able to hit each other that causes the high back pressure. Its just kills flow. End of story.

It was my understanding that the "wall" in the o2 housing caused the loss in performance. Thanks for the explaination (again).

Don't you understand that if you take away this horrible flow with a better designed O2 housing, you also take away the boost creep elimination of the non-divided mod? You're reverse engineering your way back to a fully divided housing.

This is what I was looking for.

 

[MyBeatGSX]

Sorry I sounded like a jerk, but I thought we already.

 

[DGajre777]

Sorry I sounded like a jerk, but I thought we already.

I thought we too, but then I saw that review on the Lipp o2 housing and I went, "Hmmmm....."

 

[MrBoxx]

I'm glad you guys didn't have to come to blows over this. Your debates made for good reading, though, I must say.

 

[92awddsm]

Nevermind, my mistake.

 

[kenamond]

Not trying to add fuel to the fire buy you have this backwards. The divided mod creates turbulence at the turbine outlet. The non-divided housing flows better and causes the creep.

I thought that's what he said.

Couple of points. The divided housing will disrupt turbine outlet flow increasing pressure just downwind of the turbine wheel which decreases the torque on the turbine wheel. However, it helps the WG flow, too. This is because the WG flapper doesn't open much, and with a divided housing, the gated exhaust hits the divider and hinders flow out the WG. If you remove the divider, the gated exhaust has less problem getting past the flapper. But the solution is to keep the nice turbine exit flow AND let the WG dump sufficient exhaust to keep the boost under control.

You can do this by using an external gate, maybe porting, or running at or above the level of boost that it creeps to. Or you could have a WGA with a longer throw that also can hold the flapper closed while building boost. Or you could have a WG in the O2 housing that is like an external WG design and flows better than the flapper style.

 

[MyBeatGSX]

Not trying to add fuel to the fire buy you have this backwards. The divided mod creates turbulence at the turbine outlet. The non-divided housing flows better and causes the creep.

What I said is correct. You restated it half backwards and fully wrong.

Non-divided, I.E. what was just linked to a few posts back: very turbulent, doesn't creep

Divided, I.E. stock setup: smooth flow, lots of creep


If the non-divided housing caused creep, then why would people do it?

Let me try one final time, everyone repeat after me... slowly now....

Non-divided housings cure creep by destroying turbine discharge flow. There is no benefit to this modification. If you love ghetto hacking that much, put your stock exhaust back on and it will have the same effect.

 

[MyBeatGSX]

with a divided housing, the gated exhaust hits the divider and hinders flow out the WG. If you remove the divider, the gated exhaust has less problem getting past the flapper.

NO NO NO NO NO!!!

This is NOT why it prevents the creep. This mod does NOTHING TO AID WASTEGATE FLOW.

It stops creep by HURTING turbine flow. It DOES NOT help wastegate flow, please try to understand this. A stock wastegate discharge area and O2 housing wastegate discharge area flows much more than the actual flapper/wastegate passage itself will let through, just compare the areas with your eyes and use common sense.

Please people, this is so simple to understand, why do you make it so difficult. What gets me the most is that this is a well know and proved fact in every other automotive community, why is it such a difficult to understand and foreign concept here?

IT CURES CREEP BY HURTING TURBINE DISCHARGE FLOW. No other way, that's it, over, done, end of story. That's ALL it does.

 

[92awddsm]

What I said is correct. You restated it half backwards and fully wrong.

Non-divided, I.E. what was just linked to a few posts back: very turbulent, doesn't creep

Divided, I.E. stock setup: smooth flow, lots of creep


If the non-divided housing caused creep, then why would people do it?

Let me try one final time, everyone repeat after me... slowly now....

Non-divided housings cure creep by destroying turbine discharge flow. There is no benefit to this modification. If you love ghetto hacking that much, put your stock exhaust back on and it will have the same effect.

Calm down, you're right. I was thinking of non cut divider and cut divider. Thats what 6 hrs sleep in 3 days does to you. I already corrected my previous post.

 

[MyBeatGSX]

I am calm. This is what not being able to sleep because its too hot in my room does to me.

 

[kenamond]

What I said is correct. You restated it half backwards and fully wrong.

Non-divided, I.E. what was just linked to a few posts back: very turbulent, doesn't creep

Divided, I.E. stock setup: smooth flow, lots of creep


If the non-divided housing caused creep, then why would people do it?

Let me try one final time, everyone repeat after me... slowly now....

Non-divided housings cure creep by destroying turbine discharge flow. There is no benefit to this modification. If you love ghetto hacking that much, put your stock exhaust back on and it will have the same effect.

Harsh, Tyler I'd say he was half backward and half right...but that the rest of your post is 100% correct. Folks also need to keep in mind that at full boost, exhaust is gushing out the WG but still flowing through the turbine. They are happily in equilibrium; the turbine gets fed just enough to drive the compressor to generate the desired level of boost, and the rest is gushing out the WG. Also, this is when you want a highly efficient system (WOT, full boost). So if you tinker with the turbine inlet or outlet flow, you're decreasing the efficiency of the turbine system, and injecting that WG flow into the path of the turbine exit flow will DEFINITELY tinker with it.

 

[MyBeatGSX]

Hurray. We've reached a consensus. Quickly, someone lock the topic before another question gets asked!

 

[kenamond]

NO NO NO NO NO!!!

This is NOT why it prevents the creep. This mod does NOTHING TO AID WASTEGATE FLOW.

It stops creep by HURTING turbine flow. It DOES NOT help wastegate flow, please try to understand this. A stock wastegate discharge area and O2 housing wastegate discharge area flows much more than the actual flapper/wastegate passage itself will let through, just compare the areas with your eyes and use common sense.

Please people, this is so simple to understand, why do you make it so difficult. What gets me the most is that this is a well know and proved fact in every other automotive community, why is it such a difficult to understand and foreign concept here?

IT CURES CREEP BY HURTING TURBINE DISCHARGE FLOW. No other way, that's it, over, done, end of story. That's ALL it does.

Though I agree that the disruption in turbine exit flow is most likely the reason this hack fixes creep, I'm not convinced that it doesn't help WG flow. The flapper diverts the WG exhaust right at that divider (the well known tan marks on the divider in that VFAQ porting article), and removing it makes it easier for the gas to get out. But that's not all that pertinent, because you're hurting performance. If the divider is thick enough, porting part of the divider (not all the way through) such that the WG exhaust is deflected downstream would help WG flow, but you still preserve the clean turbine exit flow.

 

[MyBeatGSX]

Ok so then I'll be the dumbass that brings up the next question... a question no one ever has or ever will answer for me.

Why don't MHI wastegate flappers open 90*? They designed the discharge area shape to clear a wastegate that opens 90* (I'm refering to the O2 housing and the shape/depth of the discharge area), but yet it doesn't? This inability to open far enough probably accounts for 90% of the creep we get.

 

[kenamond]

Ok so then I'll be the dumbass that brings up the next question... a question no one ever has or ever will answer for me.

Why don't MHI wastegate flappers open 90*? They designed the discharge area shape to clear a wastegate that opens 90* (I'm refering to the O2 housing and the shape/depth of the discharge area), but yet it doesn't? This inability to open far enough probably accounts for 90% of the creep we get.

Amen brotha.

 

[oldman]

Why don't MHI wastegate flappers open 90*? They designed the discharge area shape to clear a wastegate that opens 90* (I'm refering to the O2 housing and the shape/depth of the discharge area), but yet it doesn't? This inability to open far enough probably accounts for 90% of the creep we get.

Because it works with the stock exhaust?

 

[kenamond]

Because it works with the stock exhaust?

Heh. I guess my question is, "Why hasn't someone found/adapted a WGA that *will* open the flapper sufficiently?"

 

[oldman]

Heh. I guess my question is, "Why hasn't someone found/adapted a WGA that *will* open the flapper sufficiently?"

I think this is a factor but I disagree with the notion that this is the biggest contributor to boost creep, the fact that porting alone can cure boost creep proves that.

 

[kenamond]

I think this is a factor but I disagree with the notion that this is the biggest contributor to boost creep, the fact that porting alone can cure boost creep proves that.

That suggests that the WGA is close to being able to do it on its own. I suspect that a WGA that opens the flapper more and can also hold it closed would do the trick, and if it's a bolt-on part, it'd be much easier than porting, maybe cheaper, too.

I guess we won't know unless someone finds a better WGA.

 

[mavisky]

I've always been a fan of having the right supporting mods for whatever turbo I'm on. Sure my 18g tends to creep a little bit, but since it's set at 20psi it doesn't matter since it never creeps past 15 or 16.

 

[MyBeatGSX]

That suggests that the WGA is close to being able to do it on its own. I suspect that a WGA that opens the flapper more and can also hold it closed would do the trick, and if it's a bolt-on part, it'd be much easier than porting, maybe cheaper, too.

Agreed.

And it won't hurt the internal flow like porting does either. If they were meant to be ported it would come like from the factory.